public class Example3_6 {
   public static void main(String args[]) {
      double sum = 0,item = 1;
      int i = 1,n = 20;
      while(i<=n) {
         sum = sum+item;
         i = i+1;
         item = item*(1.0/i);
      }
      System.out.println("sum="+sum);
   }
}

